For minimizing the fuel consumption of motor vehicles, aerodynamically favorable design of the outer vehicle body proves to be particularly favorable. At the motor vehicle rear end it proves to be advantageous when the transition from a motor vehicle side wall towards a rear window is configured aerodynamically. Comparatively small curvature radii or abruptly changing outer contours of the motor vehicle body can improve the vehicle aerodynamics. For example, the transition from a side wall to a rear window in the region above the belt line of the motor vehicle, cause so-called aerodynamic stall which can lead to an undesired increase of the air resistance of the motor vehicle body.
To improve the aerodynamic characteristics of motor vehicles, side spoilers are therefore known which can be arranged on a vehicle side door or on the window frame of a rear window, approximately between belt line and upper window frame of the rear window. Such a side spoiler is known for example from DE 10 2009 011 063 A1.
Such side spoilers are fastened separately to a window frame of a tailgate or to a side wall. The side spoiler in this case exclusively has a function which improves the aerodynamics of the motor vehicle.